Hi,
is there a way to use interface default methods in Kawa?

suppose that I have an interface defined like this:

(define-simple-class I () interface: #t
  ((m key) #!abstract)
  ((contains key)::boolean (not (eq? #!null (m key)))))

When I try running this raw, Kawa complains:

Exception in thread "main" java.lang.ClassFormatError: Code attribute in
native or abstract methods in class file I

But when I try to add allocation: 'default or access: 'default before the
method's body, I get either

unknown allocation specifier

or

unknown access specifier (quote default)

error. I haven't found any mention of "default methods" in the Kawa manual,
so I wonder whether this feature is supported, or whether it would be hard
to add support for it to Kawa.

Best regards,
Panicz